The present invention concerns an improved contact lens disinfecting device.
Use of hydrogen peroxide for the chemical sterilization or disinfecting of soft contact lenses is well-known in the art. Such lenses are generally disinfected inside particularly-crafted contact lens holders. For example, U.S. Pat. No. 4,637,919 discloses a lens disinfecting appliance with an improved venting feature for use with oxidative disinfectants. The venting feature in the '919 patent is a filter cartridge inserted into an aperture. This allows oxygen produced by decomposing hydrogen peroxide to escape from the device.
The purpose for venting in a contact lens disinfecting appliance is to allow oxygen to escape. Hydrogen peroxide is an oxidative disinfectant, that is, as part of the disinfection process, the hydrogen peroxide breaks down into water and oxygen. For such disinfection systems, the appliance containing the lenses and the disinfectant must be designed to allow oxygen to escape from the appliance or the appliance might explode due to the build up of vapor pressure.
Other attempts to solve the problem of providing a contact lens disinfecting device which can vent the oxygen produced by decomposing hydrogen peroxide include U.S. Pat. No. 4,396,583. In the '583 patent, a contact lens disinfection appliance which can vent oxygen is disclosed. In the appliance a gas-permeable, liquid-impermeable membrane is loosely fitted inside a space in a cap of the device. The membrane is positioned between the disinfecting chamber and apertures located in the cap. The apertures in the cap allow gas which has passed through the membrane to escape.
Unfortunately, neither the invention disclosed in the '583 patent nor in the '919 patent adequately solves the problem of venting the oxygen created during hydrogen peroxide decomposition while providing a leak-proof and non-clogging appliance. The '919 patent provides an appliance with minimal surface area to allow oxygen to escape. In addition, leakage is a potential problem as the filter cartridge is not adequately secured inside the aperture into which it is placed. Moreover, the filter cartridge would have a tendency to clog because of its minimal surface area.
The appliance disclosed in the '583 patent is also inadequate because it provides a membrane which can be easily dislodged. Since this membrane in the appliance in the '583 patent can be easily dislodged, the appliance is likely to leak.
The present invention solves the problems of the prior art by providing a contact lens disinfecting appliance with a gas-permeable, liquid-impermeable member fixed securely thereto which can properly and adequately vent oxygen created during hydrogen peroxide decomposition without clogging or leaking.